It is proposed to continue the work along the lines specified in the report. Studies will be commenced on the sequence of amino acids in the vicinity of the essential lysine and the essential cysteine of UDPG-dehydrogenase. Further work is planned on the role of the subunits structure of both UDPG-dehydrogenase and histidinol dehydrogenase. Attempts will be made to relate the function of both of these four-electron NAD-linked dehydrogenases to the two-electron alcohol dehydrogenase and glutamate dehydrogenase, both of which have been shown to involve an essential lysine group. BIBLIOGRAPHIC REFERENCES: Mechanism of Action of Uridine Diphosphoglucose Dehydrogenase: Evidence for a Second Reversible Dehydrogenation Step Involving an Essential Thiol Group. W.P. Ridley, J.P. Houchins and S. Kirkwood. J. Biol. Chem. 250, 8761-8767 (1975). Mechanism of Action of UDPG-dehydrogenase. Evidence for an Essential Lysine as the Active Site. A. B. Ordman and S. Kirkwood. J. Biol. Chem., in press, 1975.